function getDistance(lat1, lng1, lat2, lng2) {
    const R = 6378137
    let dis = 0
    let radLat1 = toRadians(lat1)
    let radLat2 = toRadians(lat2)
    let deltaLat = radLat1 - radLat2
    let deltaLng = toRadians(lng1) - toRadians(lng2)
    dis = 2 * R * Math.asin(Math.sqrt(Math.pow(Math.sin(deltaLat / 2), 2) +
        Math.cos(radLat1) * Math.cos(radLat2) * Math.pow(Math.sin(deltaLng / 2), 2)))
    return dis
}
function toRadians(d) {
    return d * Math.PI / 180
}
module.exports = {
    getDistance
}